1. Field of the Invention
The present general inventive concept relates to a fusing unit usable with an electrophotographic image forming apparatus which fuses an image onto a recording medium, such as a paper, in which a toner image is transferred, by applying heat and pressure, and more particularly, to a belt type fusing unit which includes a main roller and a fusing belt to rotate in contact with a portion of an outer circumferential surface of the main roller, wherein the fusing belt has a tension portion and a non-tension portion.
2. Description of the Related Art
Common image forming apparatuses, such as a laser beam printer, an LED printer, a digital copy machine, and a facsimile, transfer an image onto a paper as a visible image in response to a digital signal input from a computer or a scanner.
Electrophotographic image forming apparatuses form an electrostatic latent image corresponding to a desired image onto an outer circumferential surface of a photoconductor by exposing light to the outer circumferential surface of the photoconductor in response to a digital signal corresponding to the desired image to be printed using a predetermined pattern, develop the electrostatic latent image using a power type toner, transfer the developed image onto a paper directly or via a transfer medium, and perform a fusing process thereon.
As mentioned above, the electrophotographic image forming apparatus includes a fusing unit which fuses a toner image (i.e., the developed image) transferred onto the paper by applying heat and pressure. A conventional fusing unit used in the electrophotographic image forming apparatus includes a roller type fusing unit and a belt type fusing unit. Compared to the roller type fusing unit, the belt type fusing unit can ensure a long nip section, so that a fusing temperature can be lowered. In addition, since a belt having a small heat capacity is used, a heat transfer efficiency can be improved.
In the belt type fusing unit, the belt is pressurized towards a main roller to apply a tension to the belt. Since the belt is made of a material having a form of a thin film and is continuously subjected to a tension stress in a high temperature environment, deformation of the belt frequently occurs. In addition, a lifespan of the belt is severely reduced due to the high temperature environment and the tension. Additionally, if slipping or meandering occurs when a predetermined tension is applied, it is difficult to control the applied tension or to fix the slipping or meandering.